[v1][mamba] Added mamba_type into MambaSpec (#21715)

Signed-off-by: asafg <asafg@ai21.com>
Co-authored-by: asafg <asafg@ai21.com>

vllm/v1/attention/backends/mamba_selectors.py

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from vllm.attention.backends.abstract import AttentionBackend
+from vllm.v1.attention.backends.mamba_attn import Mamba2AttentionBackend
+
+
+def get_mamba_attn_backend(mamba_type: str) -> type[AttentionBackend]:
+    if mamba_type == "mamba2":
+        return Mamba2AttentionBackend
+
+    raise NotImplementedError(f"Mamba Attention type {mamba_type} is not "
+                              "supported yet.")